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Phycoplast
image:Phycoplast.png, Schematic representation of types of cytokinesis in the green algae: 1) Phycoplast formation with cleavage furrow (e.g. ''Chlamydomonas''); 2) Cleavage furrow and persistent telophase spindle (e.g. ''Klebsormidium''); 3) Phycoplast and cell plate formation (e.g. ''Fritschiella''); 4) Persistent telophase spindle/phragmoplast with cell plate formation (e.g. ''Coleochaete'') The phycoplast is a microtubule structure observed during cytokinesis in members of the '' Chlorophytina'', the largest and most well known subphylum of chlorophyte green algae. Cytokinesis in green algae occurs via a diverse range of mechanisms, including cleavage furrows in some algae and cell plates in others. Plants (=Chloroplastida) of the clade ''Phragmoplastophyta'' (a subgroup of charophytes which includes the land plants, desmids, water silk, stoneworts etc.) use structures called phragmoplasts to organize and guide the growing cell plate. In these plants, the microtubules of the ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Phycoplast
image:Phycoplast.png, Schematic representation of types of cytokinesis in the green algae: 1) Phycoplast formation with cleavage furrow (e.g. ''Chlamydomonas''); 2) Cleavage furrow and persistent telophase spindle (e.g. ''Klebsormidium''); 3) Phycoplast and cell plate formation (e.g. ''Fritschiella''); 4) Persistent telophase spindle/phragmoplast with cell plate formation (e.g. ''Coleochaete'') The phycoplast is a microtubule structure observed during cytokinesis in members of the '' Chlorophytina'', the largest and most well known subphylum of chlorophyte green algae. Cytokinesis in green algae occurs via a diverse range of mechanisms, including cleavage furrows in some algae and cell plates in others. Plants (=Chloroplastida) of the clade ''Phragmoplastophyta'' (a subgroup of charophytes which includes the land plants, desmids, water silk, stoneworts etc.) use structures called phragmoplasts to organize and guide the growing cell plate. In these plants, the microtubules of the ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Phragmoplast
image:Phragmoplast.png, 300px, Phragmoplast and cell plate formation in a plant cell during cytokinesis. Left side: Phragmoplast forms and cell plate starts to assemble in the center of the cell. Towards the right: Phragmoplast enlarges in a donut-shape towards the outside of the cell, leaving behind mature cell plate in the center. The cell plate will transform into the new cell wall once cytokinesis is complete. The ''phragmoplast'' is a plant cell specific structure that forms during late cytokinesis. It serves as a scaffold for cell plate assembly and subsequent formation of a new cell wall separating the two daughter cells. The phragmoplast can only be observed in Phragmoplastophyta, a clade that includes the Coleochaetophyceae, Zygnematophyceae, Mesotaeniaceae, and Embryophyta (land plants). Some algae use another type of microtubule array, a phycoplast, during cytokinesis.P.H. Raven, R.F. Evert, S.E. Eichhorn (2005): ''Biology of Plants'', 7th Edition, W.H. Freeman and Compa ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Mitosis
In cell biology, mitosis () is a part of the cell cycle in which replicated chromosomes are separated into two new nuclei. Cell division by mitosis gives rise to genetically identical cells in which the total number of chromosomes is maintained. Therefore, mitosis is also known as equational division. In general, mitosis is preceded by S phase of interphase (during which DNA replication occurs) and is often followed by telophase and cytokinesis; which divides the cytoplasm, organelles and cell membrane of one cell into two new cells containing roughly equal shares of these cellular components. The different stages of mitosis altogether define the mitotic (M) phase of an animal cell cycle—the division of the mother cell into two daughter cells genetically identical to each other. The process of mitosis is divided into stages corresponding to the completion of one set of activities and the start of the next. These stages are preprophase (specific to plant cells), prophase ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Mitosis
In cell biology, mitosis () is a part of the cell cycle in which replicated chromosomes are separated into two new nuclei. Cell division by mitosis gives rise to genetically identical cells in which the total number of chromosomes is maintained. Therefore, mitosis is also known as equational division. In general, mitosis is preceded by S phase of interphase (during which DNA replication occurs) and is often followed by telophase and cytokinesis; which divides the cytoplasm, organelles and cell membrane of one cell into two new cells containing roughly equal shares of these cellular components. The different stages of mitosis altogether define the mitotic (M) phase of an animal cell cycle—the division of the mother cell into two daughter cells genetically identical to each other. The process of mitosis is divided into stages corresponding to the completion of one set of activities and the start of the next. These stages are preprophase (specific to plant cells), prophase ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Chlorophytina
The Chlorophytina are a proposed basal Tetraphytina clade. It is currently seen as sister of the Pedinomonadaceae. It contains the more well-known green alga and is characterized by the presence of phycoplast image:Phycoplast.png, Schematic representation of types of cytokinesis in the green algae: 1) Phycoplast formation with cleavage furrow (e.g. ''Chlamydomonas''); 2) Cleavage furrow and persistent telophase spindle (e.g. ''Klebsormidium''); 3) Phycop ...s. Below is a consensus reconstruction of green algal relationships, mainly based on molecular data et al. References {{Taxonbar, from=Q21381627 Chlorophyta Plant unranked clades ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Chlorophyte
Chlorophyta or Prasinophyta is a taxon of green algae informally called chlorophytes. The name is used in two very different senses, so care is needed to determine the use by a particular author. In older classification systems, it refers to a highly paraphyletic group of ''all'' the green algae within the green plants (Viridiplantae) and thus includes about 7,000 species of mostly aquatic photosynthetic eukaryotic organisms. In newer classifications, it refers to the sister clade of the streptophytes/charophytes. The clade Streptophyta consists of the Charophyta in which the Embryophyta (land plants) emerged. In this latter sense the Chlorophyta includes only about 4,300 species. About 90% of all known species live in freshwater. Like the land plants (embryophytes: bryophytes and tracheophytes), green algae (chlorophytes and charophytes besides embryophytes) contain chlorophyll a and chlorophyll b and store food as starch in their plastids. With the exception of Palmophyllop ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cell Cycle
The cell cycle, or cell-division cycle, is the series of events that take place in a cell that cause it to divide into two daughter cells. These events include the duplication of its DNA (DNA replication) and some of its organelles, and subsequently the partitioning of its cytoplasm, chromosomes and other components into two daughter cells in a process called cell division. In cells with nuclei ( eukaryotes, i.e., animal, plant, fungal, and protist cells), the cell cycle is divided into two main stages: interphase and the mitotic (M) phase (including mitosis and cytokinesis). During interphase, the cell grows, accumulating nutrients needed for mitosis, and replicates its DNA and some of its organelles. During the mitotic phase, the replicated chromosomes, organelles, and cytoplasm separate into two new daughter cells. To ensure the proper replication of cellular components and division, there are control mechanisms known as cell cycle checkpoints after each of the key steps ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Nuclear Envelope
The nuclear envelope, also known as the nuclear membrane, is made up of two lipid bilayer membranes that in eukaryotic cells surround the nucleus, which encloses the genetic material. The nuclear envelope consists of two lipid bilayer membranes: an inner nuclear membrane and an outer nuclear membrane. The space between the membranes is called the perinuclear space. It is usually about 10–50 nm wide. The outer nuclear membrane is continuous with the endoplasmic reticulum membrane. The nuclear envelope has many nuclear pores that allow materials to move between the cytosol and the nucleus. Intermediate filament proteins called lamins form a structure called the nuclear lamina on the inner aspect of the inner nuclear membrane and give structural support to the nucleus. Structure The nuclear envelope is made up of two lipid bilayer membranes, an inner nuclear membrane and an outer nuclear membrane. These membranes are connected to each other by nuclear pores. Two sets of in ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cytokinesis
Cytokinesis () is the part of the cell division process during which the cytoplasm of a single eukaryotic cell divides into two daughter cells. Cytoplasmic division begins during or after the late stages of nuclear division in mitosis and meiosis. During cytokinesis the spindle apparatus partitions and transports duplicated chromatids into the cytoplasm of the separating daughter cells. It thereby ensures that chromosome number and complement are maintained from one generation to the next and that, except in special cases, the daughter cells will be functional copies of the parent cell. After the completion of the telophase and cytokinesis, each daughter cell enters the interphase of the cell cycle. Particular functions demand various deviations from the process of symmetrical cytokinesis; for example in oogenesis in animals the ovum takes almost all the cytoplasm and organelles. This leaves very little for the resulting polar bodies, which in most species die without function, ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Chlorophyceae
The Chlorophyceae are one of the classes of green algae, distinguished mainly on the basis of ultrastructural morphology. They are usually green due to the dominance of pigments chlorophyll a and chlorophyll b. The chloroplast may be discoid, plate-like, reticulate, cup-shaped, spiral or ribbon shaped in different species. Most of the members have one or more storage bodies called pyrenoids located in the chloroplast. Pyrenoids contain protein besides starch. Some green algae may store food in the form of oil droplets. They usually have a cell wall made up of an inner layer of cellulose and outer layer of pectose. General characteristics * the body may be unicellular, colonial, filamentous or multicellular. * They are usually green due to the presence of chlorophyll a, chlorophyll b and beta-carotene. * The chloroplast may be discoid, cup-shaped (e.g. ''Chlamydomonas''), spiral or ribbon shaped * Most chlorophytes have one or more storage bodies called pyrenoids (central prot ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Mitotic Spindle
In cell biology, the spindle apparatus refers to the cytoskeletal structure of eukaryotic cells that forms during cell division to separate sister chromatids between daughter cells. It is referred to as the mitotic spindle during mitosis, a process that produces genetically identical daughter cells, or the meiotic spindle during meiosis, a process that produces gametes with half the number of chromosomes of the parent cell. Besides chromosomes, the spindle apparatus is composed of hundreds of proteins. Microtubules comprise the most abundant components of the machinery. Spindle structure Attachment of microtubules to chromosomes is mediated by kinetochores, which actively monitor spindle formation and prevent premature anaphase onset. Microtubule polymerization and depolymerization dynamic drive chromosome congression. Depolymerization of microtubules generates tension at kinetochores; bipolar attachment of sister kinetochores to microtubules emanating from opposite cell pol ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Telophase
Telophase () is the final stage in both meiosis and mitosis in a eukaryotic cell. During telophase, the effects of prophase and prometaphase (the nucleolus and nuclear membrane disintegrating) are reversed. As chromosomes reach the cell poles, a nuclear envelope is re-assembled around each set of chromatids, the nucleoli reappear, and chromosomes begin to decondense back into the expanded chromatin that is present during interphase. The mitotic spindle is disassembled and remaining spindle microtubules are depolymerized. Telophase accounts for approximately 2% of the cell cycle's duration. Cytokinesis typically begins before late telophase and, when complete, segregates the two daughter nuclei between a pair of separate daughter cells. Telophase is primarily driven by the dephosphorylation In biochemistry, dephosphorylation is the removal of a phosphate (PO43−) group from an organic compound by hydrolysis. It is a reversible post-translational modification. Dephosphoryla ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
